DESCRIPTION: This application describes a comprehensive research project designed to systematically and prospectively examine the relationship between peritraumatic psychophysiological responses to traumatic stress and subsequent posttraumatic distress and psychopathology. Previous research has demonstrated altered neuroendocrine levels in posttraumatic stress disorder (PTSD) patients, and researchers have hypothesized that trauma victims who subsequently develop PTSD may differ during their initial responses to the trauma from those victims who do not develop PTSD. This suggests that certain victims may be predisposed to developing PTSD after a traumatic event. However, these hypotheses have not been tested. The proposed research will examine serious motor vehicle accident (MVA) victims during their stay in the hospital, and repeatedly after the accident. Urinary hormone levels and acute-phase posttraumatic psychological responses will be used to test if patients who do and do not develop acute stress disorder (ASD) or PTSD differ in psychophysiological reactivity to the accident. Further, the effects of traumatic stress and PTSD on chronic alterations in neuroendocrine and immune levels will be assessed. Finally, as PTSD is more common in those with a history of psychopathology and/or prior trauma experience, the proposed research will test whether peritraumatic responding to the MVA mediates the relationship between prior trauma history and subsequent PTSD.